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Problem Description

The blood ionized calcium concentration (Ca2+, iCa) is tightly regulated in animals ranging from the most primitive fishes and nonvertebrates to humans. This is because iCa is utilized by diverse cell types as a transcellular and intracellular signaling molecule, such as in the nervous system, cardiac and skeletal muscle, epithelial cells,
endocrine cells, blood cells, among others. The blood ionized calcium concentration is approximately 1.5 mM in all animals. If the concentration changes by as little as 10-20% dysregulation of body systems (such as the neuromuscular system) will result and can be fatal. Therefore, there are multiple, redundant regulatory systems that exist to maintain blood calcium in a narrow biological range.

Mathematical modeling of blood iCa would be a useful tool to model potential effects of different diseases, drugs, or environmental chemicals on the adaptive and counterregulatory mechanisms involved in calcium balance at the organismal level. There is an abundance of empirical data in the literature on regulation of blood calcium in normal or diseased animals and humans.